Sheet 10: comparison of solutions A and B (engine/gearbox speed), 11 March 1933

In this document

This sheet dated 11 March 1933 p. 33 is a handwritten work page devoted to the comparison of two technical solutions, noted Ⓐ and Ⓑ, concerning the relationship between an "engine speed" (M) and a "gearbox speed" (B), linked by a third element noted "S" p. 33.

Diagram and notations

At the top of the page are a small sketch of a vehicle silhouette and a central technical diagram: a horizontal shaft passing through two discs, one annotated "M", the other "B", surmounted by a small spring mechanism associated with the letter "S" p. 33.

A column of four relationships is sketched under the circle "Ⓑ": M = B, M > B, M < B, M = B, each associated with a ratio "S/+" or "S/-" p. 33.

Solutions Ⓐ and Ⓑ

Solution Ⓐ is presented in connection with an underlined but crossed-out word, followed by "engine speed" p. 33. Solution Ⓑ includes a similar annotation, with the clarification in parentheses "increase M and B etc + etc =" p. 33.

Numbered list (solution Ⓐ)

A list then develops solution Ⓐ according to four cases:

A final diagram at the bottom of the page shows a spring mechanism with a spoked wheel and movement arrows annotated "+" and "-" p. 33.

Context

This sheet is part of the research conducted by Paul Magès within the Citroën studies in the early 1930s. Having joined Citroën in August 1925 at 17 and a half as a self-taught person, technical writer and then deputy head of the Super-Control (autobiographical notes), he was then exploring various transmission and engine/gearbox regulation architectures, prior to the work that would lead, from the end of the 1930s and especially from 1944, to the hydropneumatic suspension (plans of 17 February 1944). The M/B/S notation and the comparison of alternative solutions evoke an engineer's approach seeking to model, through sketches and simple relationships, the behaviour of an engine-gearbox pair according to different operating hypotheses — but no reference to a specific vehicle model appears in the document itself.

Archivist's view

This sheet appears to be a page of preparatory calculation and reflection, probably intended to compare two assemblies or settings (Ⓐ and Ⓑ) according to their behaviour in acceleration and deceleration p. 33. The presence of crossed-out words and uncertain passages suggests a raw working document, not intended to be presented as is.

It likely belongs to the same set of studies as the handwritten folder "1933", which mentions work on speeds and transmission components — this sheet dated 11 March 1933 could constitute a detail piece of it. The rigour of the symbolic notation (M, B, S) testifies to a systematic working method characteristic of Magès' notebooks from this period, nearly a decade before these reflections found their culmination in the first hydropneumatic suspension plans of 1944 and then the 2 CV tests in 1946.